Just wanted to clear up some of the confusion about the place of carbohydrates in our daily dietary intake...
1. What is the main function of carbohydrates in the body?
Carbohydrates are the body’s main fuel source. They are an essential part of a healthy diet, despite being given a bad rap at times. They offer multiple vitamins, minerals and other nutrients as well. Carbohydrates, when broken down into glucose (a type of sugar), provide stable glucose levels in the body. They essentially spare the body from using fat and protein as an energy source. When protein is used as an energy source, it is not available to build muscle. Carbohydrates fulfill the body’s immediate energy needs, while fats and protein are long-term energy sources. Carbohydrates are easier and quickly broken down, thus, the body prefers carbohydrates.
2. What is the difference between sugars, starches and fibers?
Carbohydrates, which are either fiber, starch or sugar, are either simple of complex. Simple carbohydrates are quickly digested and absorbed by the body; complex carbohydrates are digested over a longer period.
Dietary fiber (a complex carbohydrate) is either soluble or insoluble. Soluble fiber, unlike insoluble fiber, absorbs water. It regulates blood glucose levels and lowers cholesterol. Sources of soluble fiber include dried beans and peas, oats, barley, apples and citrus fruits. Insoluble fiber is beneficial to intestinal health and is usually found in whole grains, vegetables and fruits. Fiber slows down the digestive process, thereby, allowing food to break down slowly, creating a feeling of fullness and satiety, and decreasing spikes in blood sugar and insulin.
Starch (another complex carbohydrate) is the main dietary source of carbohydrate for the body and is the most common carbohydrate in our diets. It is the storage source of energy and is slowly digested and converted to blood glucose which is absorbed into the bloodstream. Starch is a component of grain products, beans, potatoes, peas and corn.
Sugar is a simple carbohydrate. It is a direct energy source and, unlike fiber and starch, breaks down quickly and is easily converted to glucose. Simple sugars are either naturally occurring (as seen in fruits, milk, honey) or found in highly processed foods (e.g., sodas, cakes, cookies, ice cream). These types of sugars are quickly digested and can be used immediately for energy. However, they cause spikes in blood sugar levels which usually results in a “crash” when blood sugar drops. Unfortunately, simple sugars are prevalent in the average American diet. Excess simple sugars are usually converted to stores of energy, or fat.
3. Functionally, what is the difference between added sugars and the naturally occurring ones in fruits, vegetables, dairy, etc.?
There are only two forms of naturally occurring sugars – lactose (found in milk) and fructose (found in fruit). Although natural sugars are carbohydrates, food sources containing these types of sugars have way more nutrients (i.e., vitamins, minerals and fiber) than foods containing added sugars such as sugary beverages, candy, cookies and flavored yogurt. Added sugars are sweeteners added to foods to make them taste sweeter. They may be listed as brown sugar, pure cane sugar, turbinado sugar, coconut sugar, raw sugar, molasses, maple syrup, honey, corn syrup, brown rice syrup, evaporated cane juice, and high fructose corn syrup – to name a few. These types of sugars provide unnecessary calories, very little nutrients and are referred to as “empty calories”. According to the American Heart Association, daily added sugar intake should be limited to 36 grams for men and 25g for women.
4. What is the thinking behind low-carbohydrate diets? Are they actually good for overall health?
A rapid rise in blood sugar ensues after ingesting high-carbohydrate foods, thus causing the body to produce insulin (a hormone responsible for transporting sugar to cells). Cells use this sugar for energy, however, excessive sugar is stored as fat. Low carbohydrate diets are beneficial for those with fat loss goals as decreased carbohydrate intake lowers insulin levels, which causes the body to utilize stored fat for energy and ultimately results in weight loss. Low carbohydrate diets rid excess water from the body and lowers insulin levels which results in early short-term rapid weight loss. These diets, however, do restrict the body’s preferred energy source – carbohydrates.
Severe carbohydrate restriction (e.g., ketogenic diet) can result in ketosis, a process in which ketones are produced as a result of the body’s breakdown of stored fat secondary to the scarcity of glucose for energy. Short-term low-carbohydrate diets can be beneficial and safe, however, in the long-term, ketosis and carbohydrate deficiency can be unhealthy. Effects of long-term ketosis and carbohydrate deficiency include fatigue, bad breath, constipation, hunger, dehydration and headaches.
If you want to reduce calories from carbohydrates, focus more on reducing intake of foods containing added sugars and eat more whole grains, fruits and vegetables to maximize energy levels and avoid gastrointestinal disturbances (often experienced when eliminating high-carbohydrate, high-fiber foods).
5. How might lifestyle factors like activity level and health affect how many carbohydrates a person needs?
Carbohydrate requirements should be based on several factors: age, gender, activity level, body composition, and metabolic health. Men typically require more carbohydrate than women because of increased muscle mass. The more active you are, the more carbohydrate you need, as carbohydrates are the main source of fuel. During periods of high intensity activity, most of the energy is derived from carbohydrate. If carbohydrate intake is reduced too low, you may be unable to fuel your active lifestyle. For example, marathon runners often participate in “carb-loading” before a race. This strategy maximizes glycogen (storage form of glucose) stores, which provides the runner with the energy needed to run long distances.
People who are obese, have type 2 diabetes, or have metabolic syndrome (i.e., increased waist circumference, high blood pressure, high blood sugar, obese) require fewer carbohydrates and may benefit from reduced carbohydrate consumption.
Bottom Line: There is no “one size fits all” when it comes to carbohydrate requirements.
Thanks for reading,